Chapter 24 I’m Suffering from Information Overload (Access Databases) Clearly Visual Basic: Programming with Visual Basic 2010 2 nd Edition

Chapter 24 I’m Suffering from Information Overload (Access Databases)

Clearly Visual Basic: Programming with Visual Basic 2010

2nd Edition

Objectives

Clearly Visual Basic: Programming with Visual Basic 2010, 2nd Edition2

After studying Chapter 24, you should be able to:Define basic database terminologyConnect an application to a Microsoft Access databaseBind table and field objects to controlsCustomize a DataGridView controlHandle exceptions using the Try…Catch statementPosition the record pointer in a dataset

Keeping Good Records


Computer database Electronic file that contains an organized

collection of related informationRelational database

Stores information in tables composed of columns and rows

Field Single item of information about a person,

place, or thing

Keeping Good Records (cont’d.)


Record Group of related fields that contain all the

necessary data about a specific person, place, or thing

TableGroup of related records

Primary keyField that uniquely identifies each record in a

table

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Clearly Visual Basic: Programming with Visual Basic 2010, 2nd Edition5 5

Figure 24-1 Example of a one-table relational database



Figure 24-2CD_Number field

Primary key in parent tableCD_Number field in child table

Used solely to link song title and track information to the appropriate CD in parent table

Child tableCD_Number field is called the foreign key

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Figure 24-2 Example of a two-table relational database

Connecting …Connecting


Figure 24-3Emp_Number field is the primary keyStatus field contains the employment statusCode field identifies the employee’s

departmentData Source Configuration Wizard

Easy way to connect an application to a database

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Connecting …Connecting (cont’d.)


Figure 24-3 Data contained in the tblEmploy table

Let the Computer Do It


BindingConnecting an object to a control

Bound controlsThe connected controls

DataGridView control Displays data in row and columnar format,

similar to a spreadsheetOne of the most popular controls for

displaying table data

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Let the Computer Do It (cont’d.)


Figure 24-7 DataGridView control’s task list



While an application is running, you can use the BindingNavigator control to:Move from one record to the next in the

datasetAdd or delete a record and save any changes

made to the datasetComponent tray

Stores objects that do not appear in the user interface while an application is running

TableAdapter object in the component tray Connects the database to the DataSet object

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TableAdapterManager object Used to save changes made to the database

BindingSource object Provides the connection between the DataSet

and the bound controls on the FormTblEmployBindingSource in Figure 24-8:

Connects EmployeesDataSet to two bound controlsDataGridView control and BindingNavigator control

Figure 24-9Illustrates relationships

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Figure 24-8 Result of dragging the tblEmploy object to the form



Figure 24-9 Illustration of the relationships among the database, the objects in the component tray, and the bound controls

The Copy to Output Directory Property


When the Data Source Configuration Wizard connects an application to a database:It adds the database file to the application’s

project folderMethod of saving changes to a local

database file Is determined by the file’s Copy to Output

Directory property

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How Does Visual Basic Do It?


When a table or field object is dragged to the form: Computer adds the appropriate controls and

objects to the applicationA form’s Load event

Occurs when the application is started and the form is displayed for the first time

Load event procedureCode to fill a dataset with data belongs here

in most applications

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Thank You for Catching My Errors


ExceptionsHandled in Visual Basic by displaying an error

message and then abruptly terminating the application

Try…Catch statementUsed to take control of the exception

handling in your code

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Figure 24-15 Syntax and examples of the Try…Catch statement (continues)


Figure 24-15 Syntax and examples of the Try…Catch statement (cont’d.)

I’ll Use My Own Controls, Thank You


To bind an object in a dataset to an existing control on the form:Drag the object from the Data Sources

window to the controlOr click the control

Then set one or more properties in the Properties window

Appropriate property to set depends on the control you are binding

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Coding the Next Record and Previous Record Buttons


BindingSource object Uses an invisible record pointer to keep track

of the current record in the datasetPosition property

Stores the position of the record pointer Move methods

Can be used to position the record pointer in a dataset

Moves the pointer to the first, last, next, or previous record

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Figure 24-19 Syntax and examples of the BindingSource object’s Position property


Figure 24-20 Syntax and examples of the BindingSource object’s Move methods

Summary


Relational databases can contain one or more tables

Data in a relational databaseCan be displayed in any order

Most tables contain a primary key that uniquely identifies each record

To access the data stored in a database:First connect the application to the database

Summary (cont’d.)


TableAdapter object Connects a database to a DataSet object

DataGridView controlDisplays data in row and column format

Try…Catch statement Used to handle exceptions that occur while

an application is runningBindingSource object

Uses an invisible record pointer to keep track of the current record in a dataset

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Documents

Chapter 24 I’m Suffering from Information Overload (Access Databases) Clearly Visual Basic: Programming with Visual Basic 2010 2 nd Edition